1. Field of the Invention
The invention concerns an electrostatic spraying installation for spraying an electrically conductive liquid product, in particular a coating product such as a water-based paint or a metallic paint; the invention is more particularly concerned with an improvement for establishing quickly and effectively the necessary electrical insulation between the spraying device at the high-tension voltage and other parts of the installation that are grounded, for example distribution circuits and/or storage tanks for such liquids.
The invention is also concerned with an electrical insulation device for a distribution circuit for an electrically conductive liquid product.
2. Description of the Prior Art
In an electrostatic spraying installation for spraying a coating product that is a relatively good electrical conductor, for example a water-based paint as mentioned above, all parts of the circuit supplying the sprayer device must in principle be insulated from ground potential. This is not possible in the case of a large installation. For example, if the paint spraying installation is part of an automobile manufacturing plant it comprises a number of very long closed loop paint circuits which may extend across an entire portion of the plant to connect the various spraying booths to large paint storage tanks. It is necessary to provide at least one such circuit for each color and another circuit of the same kind for the solvent or cleaning product. For obvious safety reasons these circuits must be grounded. Also, inside each spraying booth the electrostatic sprayer devices are advantageously connected to a high-tension voltage source. If the paint used is electrically conductive it is therefore essential to insulate electrically the sprayer device and the high-tension voltage source from the parts of the structure that must be grounded.
A known solution to this problem involves the use of an intermediate storage tank of relatively small capacity that is electrically insulated from ground and is adapted to be supplied with coating product intermittently. A variable or switchable high-tension voltage source is then provided together with means for separating or at least electrically insulating the intermediate storage tank during phases in which the coating product is sprayed from the parts of the structure that are permanently grounded.
The invention concerns a new electrical insulation device adapted to be inserted between the parts of the structure that are grounded and those which may be at a high-tension voltage.